1. Field of the Invention
This invention relates to a particle measuring apparatus for effecting measurement of particles to be examined by applying a light to the particles to be examined and photometering light such as transmitted light or scattered light or fluorescence radiated from the particles to be examined.
2. Related Background Art
In the conventional particle measuring apparatus, for example, a flow cytometer, a light has been applied from a predetermined direction to particles to be examined such as cells flowing one by one at a high speed, and light radiated thereby from the particles to be examined, i.e., transmitted light or scattered light or fluorescence has been photometered, whereby the information regarding the diameters and natures of the particles to be examined has been obtained and the particles to be examined have been statistically analyzed from this information regarding a number of cells.
In this conventional flow cytometer, the shape and size of the light beam applied to the particles to be examined are set such that the size in the direction of flow is substantially equal to or somewhat larger than the particle to be examined and the size in a direction orthogonal to the direction of flow is larger than the particle to be examined, whereby light application can be accomplished with a uniform intensity even if there occurs deviation to the flow position of the particle to be examined. Besides this, use has also been made of the slit scan system in which a slit-shaped beam having its beam size in the direction of flow made thinner than the size of the particle to be examined is applied to thereby detect more detailed information of the particle to be examined. Recently, it has also been used to mix latex particles sensitized by an antibody with a sample material, cause the aggregation of the latex particles by antigen/antibody reaction, and detect the size of this latex aggregation by the use of a flow cytometer, thereby discriminating particular antigen in the sample material.
Also, it has generally been practised to effect analysis by the image information of particles to be examined by the use of an apparatus such as an optical microscope or an electronic microscope, apart from a flow cytometer. Particularly recently, use has also been made of an apparatus in which a cell is two-dimensionally scanned by a minute laser spot to thereby obtain a high-contrast image which is reflective of the internal structure of a cell.
In these conventional apparatuses, however, only the information of each particle to be examined as seen in one direction could be taken out and three-dimensional grasp of the particles to be examined could not be accomplished.
Also, U.S. Pat. No. 3,826,364 discloses an apparatus of a construction in which two laser sources of different wavelengths are prepared and one laser light is applied to a first portion to be examined to produce forward scattered light and the other laser light is applied to a second portion to be examined differing from the first portion to be examined to excite fluorescence. In this apparatus, however, two kinds of parameters are measured not at the same position but at different positions and therefore, when particles to be examined move from the first portion to be examined to the second portion to be examined, rotation, drift or the like occurs and the particles to be examined which are in the same state cannot always be measured from different directions.